• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.1
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• pp.99-106
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• 2018

This study presents experimental investigation on the residual capacity of fire-damaged voided slabs according to loading conditions. In this study, two voided slab specimens were fabricated, and heated by ISO standard fire during 120 minutes with different loading conditions of presence of loading. These specimens were cooled down to room temperature, and the residual capacity of fire-damaged voided slabs was investigated. Based on test results, thermal distribution of voided slab through the depth of concrete sections is different by the loading conditions. The temperature of loaded specimen is rapidly elevated through the whole depth of concrete sections compared to the unloaded specimen. The residual strength of fire-damaged voided slab specimens are 60% and 66% of that of voided slab specimen without fire damage, and the residual stiffness of fire-damaged voided slab specimens decreases by 15%~23% of that of voided slab specimen without fire damage. In case of voided slab specimens subjected ISO standard fire, the loaded specimen shows the decrease of 10% in the residual strength and the decrease of 15% in the residual stiffness compared to the unloaded specimen. It seems to result from higher temperature of bottom reinforcements in the loaded specimen due to the cracks, and more extensive damage on concrete cover of reinforcements by spalling process according to load level.

• Journal of the Korea Concrete Institute
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• v.26 no.3
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• pp.247-254
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• 2014

Strain properties of concrete member which acts as an important factor in the stability of the concrete structure in the event of fire, significantly affected the characteristics of the coarse aggregate, which accounts for most of the volume. For this reason, there are many studies on concrete using artificial lightweight aggregate which has smaller thermal expansion deformation than granite coarse aggregate. But the research is mostly limited on concrete using clay-based lightweight aggregate. Therefore, in this study, the high temperature compressive strength and elastic modulus, thermal strain and total strain, high temperature creep strain of concrete was evaluated. As a result, remaining rate of high-temperature strength of concrete using lightweight aggregate is higher than concrete with general aggregate and it is determined to be advantageous in terms of structural safety and ensuring high-temperature strength from the result of the total strain by loading and strain of thermal expansion. In addition, in the case of high-temperature creep, concrete shrinkage is increased by rising loading and temperature regardless of the type of aggregate, and concrete using lightweight aggregate shows bigger shrinkage than concrete with a granite-based aggregate. From this result, it is determined to require additional consideration on a high temperature creep strain in case of maintaining high temperature like as duration of a fire although concrete using light weight aggregate is an advantage in reducing the thermal expansion strain of the fire.

• Journal of the Korea Institute of Building Construction
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• v.15 no.6
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• pp.597-605
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• 2015

The method of concrete mix design used in this study aims to achieve the identical specified design strength, applying different types and replacement ratio of mineral admixtures and afterwards, fire tests were conducted using the standard time-temperature curve specified in the ASTM E119 to identify the influences of the types of mineral admixtures on the fire resistance performance of high strength concrete(HSC). The least spalling was observed in the test specimen containing blast furnace slag as a partial replacement of cement, while the most significant spalling phenomena were observed in the blast furnace slag test specimen that silica-fume was added in. In particular, the reasonable volume of spalling was observed when solely replaced by silica fume. However, the influence of the cement replacement by silica fume and blast furnace slag on the increases of spalling can be explained through blocked pores by the fine particles of silica fume, leading to decreases in permeability.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.3
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• pp.33-41
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• 2016

Concrete is inherently a good fire-resistance material among all other constrcution materials and protects the reinforcing steel inside. This study investigates the material characteristics of concrete and steel bar inside the full scale reinforced concrete(RC) beam exposed to fire test. The fire test specimen was 4 m long and the test was conducted under no loading condition following KS F 2257. Fire source is simulated by ISO 834 and number of thermocouples were installed to measure temperature variation of surfaces and inside of the beam. The measured compressive strength of cored specimen, which was exposed to fire test, was 11 MPa, about 66% lower than the strength before exposure. The yielding strength of steel bar also decreased about 75 MPa, about 17% lower. The measured temperature of protected steel bar was around $649^{\circ}C$, the critical limit, after 4 hour exposure.

• Fire Science and Engineering
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• v.27 no.3
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• pp.8-13
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• 2013

In case of fire in a high-rise building fire can be easily spread along the building external walls dramatically if the flame comes out through broken windows. There are a few effective methods to prevent the fire spread at the moment. One is using a fire resistance window, and the other is using a window sprinkler that discharges water to resist flame in case of fire. In this study a window sprinkler which is installed on top of windows and prevents fire by discharging water when its heat-responsive element opens was tested using a large scale furnace in accordance with the standard temperature-time graph. Test result showed that one window sprinkler was able to protect a 2,400 mm wide window from fire for 2 hours and the window backside's temperature locally increased up to $126^{\circ}C$ but kept stable around $100^{\circ}C$ for the test duration.

• Journal of the Korea Concrete Institute
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• v.21 no.4
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• pp.465-471
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• 2009

To prevent the explosive spalling of the high strength concrete and control the rise of temperature in the steel rebar during fire, a fiber cocktail method has been proposed simultaneously with the use of polypropylene and steel fiber. After applying the fiber cocktail (polypropylene and steel fibers) into the mixture of high strength concrete with a compressive strength of between 40 and 100 MPa and evaluating the thermal properties at elevated temperatures, the fire test was carried out on structural members in order to evaluate the fire resistance performance. Two column specimens were exposed to the fire without loading for 180 minutes based on the standard curve of ISO-834. No explosive spalling has been observed and the original color of specimen surface was changed to light pinkish grey. The inner temperature of concrete dropped rapidly starting from 60mm deep. After 60 minutes of exposure to the fire, the temperature gradient of fiber cocktail reinforced high strength concrete was measured as 2.2oC/mm, which is approximately 5 times less than that of normal concrete. The final temperatures of steel rebar after 180 minutes of fire test resulted in 488.0oC for corner rebar, 350.9oC for center rebar, and 419.5oC for total mean of steel rebar. The difference of mean temperature between corner and center rebar was 137.1oC The tendency of temperature rise in concrete and steel rebar changed between 100oC and 150oC The cause of decrease in temperature rise was due to the water vaporization in concrete, the lower temperature gradient of the concrete with steel and polypropylene fiber cocktails, the moisture movement toward steel rebars and the moisture clogging.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.5
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• pp.537-541
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• 1999

Fish heads of the main by-product is fishery processing were treated to extract nutrients by heating the fish heads with 1.5 or 3.0 times added water during 9, 12 or 15 hours. The yield, chemical compositions and physical properties of the hydrothermal extracts were studied. The yield was increased with the amount of water added and the extracting hours. The extract contained about $80\%$ protein in solid basis, but has no lipid. In essential amino acid, glutamic acid was most abundant and Iysine was abundant. In free amino acid, $\delta$-hydroxylysine and L-histidine in Cypyrinus carpio linnaeus had 5 times more than those in Onchorhynchus keta, The solution of the extracts was known as Newtonian fluid and the color of the extracts showed lower whiteness, higher redness and higher yellowness.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.9
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• pp.1097-1105
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• 2017

This study examined how much chicken meat was in sausage made with pork. Both real-time polymerase chain reaction (PCR) and internal standard addition were used. Fifty ng of chicken DNA was added to the sausages as an internal standard. The addition of standard DNA increased the amplification efficiency of PCR and confirmed the possibility of quantitative analysis. A QIAamp DNA Micro Kit was used to improve the DNA recovery and amplification efficiency. The density of template DNA and primer were suitable for $3.0{\sim}5.0{\mu}L$ and $0.5{\mu}L$, respectively. Each DNA of pig and chicken was diluted in 10-fold from steps 50 ng to 0.05 ng. The detection limit of both pig and chicken meat was more than 0.05 ng and the correlation coefficient of the standard curve was at least 0.98. The result of the quantitative analysis after heat treatment of 3 samples of pigs and chickens mixed at 70:30 showed a 5.7% difference (64.3:35.7) between the expected value and measured value. The quantitative value was changed by affecting the DNA according to the heat treatment ($70^{\circ}C$, 10 min). An analysis of the pork and chicken content in sausages showed that it was difficult to detect chicken meat and the quantitative value of DNA according to the Ct value was very low. On the other hand, when adding standard material (50 ng of chicken DNA) to the sausages, the Ct value decreased gradually with increasing chicken mixing ratio. Thus, the mixing ratio of chicken in sausages could be estimated.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.4
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• pp.115-122
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• 2008

This paper is to investigate the affecting factors on spalling of the high strength concrete including W/B, air content and moisture condition as well as PP fiber contents subjected to fire. An increase with 0.05% of PP fiber resulted in a reduction of slump flow by as much as 11%. Ten percent of air contents due to excessive amounts of AE agent does not lead to variance of slump flow, regardless of PP fiber content. For the effect of the compressive strength, high strength concrete with 15, 25 and 35% of W/B gained 60 MPa~100 MPa of the compressive strength. High strength concrete with H-air had half of compressive strength of that with L-air due to large amount of air. Fire test was conducted in accordance with KS F 2257-1 for 1 hour. Spalling did not occur with all specimens containing more than 0.10% of PP fiber except those with 15% of W/B. Moreover, it is interesting to note that the specimens with more than 10% of air content and with oven dried condition, respectively, had no spalling even if the content of PP fiber is 0.05 vol.%.

• Journal of the Korea Concrete Institute
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• v.21 no.4
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• pp.473-480
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• 2009

The 180 minutes fire test based on the standard curve of ISO-834 were conducted on three RC column specimens with different constant axial loading ratios to evaluate the fire performance of fiber cocktail (polypropylene+steel fiber) reinforced high strength concrete column. The columns were tested under three loading levels as 40%, 50%, and 61% of the design load. No explosive spalling has been observed and the original color of specimen surface has been changed to light pinkish grey. The maximum axial displacements of three specimens were 1.5~2.2 mm. There was no reduction in load bearing capacity of each specimen exposed to fire and no effect were observed on the fire performance within 61% of the design load. The tendencies of the results with loading, such as the temperature distribution of in concrete and the changes in temperature rise due to the water vaporization in concrete, are very similar to those without loading. The final temperatures of steel rebar after 180 minutes of fire test resulted in 491.4${^{\circ}C}$ for corner rebar, 329.0${^{\circ}C}$ for center rebar, and 409.8${^{\circ}C}$ for total mean of steel rebar. The difference of mean temperature between corner and center rebar was 153.7${^{\circ}C}$ㅍ. The tendency of temperature rise in concrete and steel rebar changed after 30~50 minutes from the starting time of the fire test because the heat energy influx into corner rebar is larger than that into center rebar. The cause of decrease in temperature rise was due to the water vaporization in concrete, the lower temperature gradient of the concrete with steel and polypropylene fiber cocktails, the moisture movement toward steel rebars and the moisture clogging.